Method of protecting electrical conductor terminations during gas panel fabrication

ABSTRACT

Thin parallel electrical conductors are protected from attack during elevated temperature operations in gas panel fabrications by a method which involves depositing the parallel electrical conductors on a pair of glass plates with the parallel conductors terminating a given distance from the edges of each glass plate whereby each such plate extends beyond the ends of the parallel conductors, and covering the parallel conductors with a protective glass coating which covers completely the top, sides, and ends of each parallel conductor. Since the ends of the parallel conductors are covered completely, they are protected from attack and destruction during subsequent firing operations in the fabrication of a gas panel. After panel fabrication is completed one end of each glass plate may be cut off flush with the ends of the parallel conductors if desired. The protective glass coating is removed around the end or terminal regions of the parallel conductors whereby the exposed portions of the conductors may serve as electrical contacts.

United States Patent [19] Wagner et al.

11] 3,778,901 1 Dec. 18, 1973 Donald M. Wilson, Kingston, both of NY.

[73] Assignee: I International Business Machines Corporation, Armonk,N.Y.

22 Filed: Dec. 30, 1971 211 Appl. No.: 214,150

[52] U.S. Cl 29/625, 29/25.]3, 29/624,

1 17/211 [51] Int. Cl. H05k 3/28 [58] Field of Search 313/220, 221;

29/25.], 25.11, 25.13, 472.5, 472.9, 625, 631, 25.16, 25.19; 316/19,l7;65/138, 139, 147, 154, 59, 36, 23; 315/169 R, 169 TU, 165; 117/201,211

Primary Examiner-Charles W. Lanham Assistant ExaminerJoseph A. WalkowskiAttorney-Ralph L. Thomas [57] ABSTRACT Thin parallel electricalconductors are protected from attack during elevated temperatureoperations in gas panel fabrications by a method which involvesdepositing the parallel electrical conductors on a pair of glass plateswith the parallel conductors terminating a given distance from the edgesof each glass plate whereby each such plate extends beyond the ends ofthe parallel conductors, and covering the parallel conductors with aprotective glass coating which covers completely the top, sides, andends of each parallel conductor. Since the ends of the parallelconductors are covered completely, they are protected from attack anddestruction during subsequent firing operations in the fabrication of agas panel. After panel fabrication is completed one end of each glassplate may be cut off flush with the ends of the parallel conductors ifdesired. The protective glass coating is removed around the end orterminal regions of the parallel conductors whereby the exposed portionsof the conductors may serve as electrical contacts.

4 Claims, 3 Drawing Figures PATENTEU DEC 1 8 i915 SKH 10? 2 METHOD OFPROTECTING ELECTRICAL CONDUCTOR TERMINATIONS DURING GAS PANELFABRICATION CROSS-REFERENCES TO RELATED APPLICATIONS Application Ser.No. 214,348 filed on Dec. 30, 1971 for Gas Panel Fabrication by Peter H.Haberland et al.

-Application Ser. No. 214,151 filed on Dec. 30, 1971 for Improved Methodof Gas Panel Construction by Thomas J. Murphy et al.

BACKGROUND OF THE INVENTION 1. This invention relates to gas panels andmore particularly to a method of constructing gas panels.

2. It is customary in the construction of gas panels to deposit verynarrow and very thin parallel lines, which serve as electricalconductors, on a pair of glass plates with the parallel lines on oneplate disposed orthoganlly with respect to the parallel lines on theother plate. The plates are spaced apart and sealed around the peripherythereof to form a chamber therebetween for holding an illuminable gas.In the past the parallel lines on each plate extended to the edge of theglass plate, and a protective glass coating disposed over the parallellines covered the side and top of each parallel line but left the endsof each parallel lines exposed. The exposed ends of the parallel lineswere subjected to attack and destruction during subsequent firingoperations in the fabrication process. As a result the regions near theends of parallel lines were pitted or eroded in some case and totallydestroyed in other cases. Pitting or erosion resulted from oxidation ofthe thin parallel lines,

and this changed their electrical characteristics. In gas panels the endor terminal regions of the parallel lines are used as electricalcontactswhich engage companion contacts of an electrical connector.Pitting or erosion resulted in defective electrical connections in somecases, and complete destruction resulted in no electrical connection inother cases. It is to the problem of preserving the end regions ofelectrical lines, useful also as reliable electrical contacts, bypreventing attack and destruction during the fabrication process thatthis invention is directed.

SUMMARY OF THE INVENTION It is a feature of this invention to provide animproved method of protecting small, thin electrical lines during thefabrication process of a gas panel.

It is a feature of this invention to provide an improved method of gaspanel construction which prevents attack and destruction of smallelectrical conductors throughout the steps of panel fabrication,especially steps involving elevated temperature firing or bakingoperations.

In a preferred method of fabricating a gas panel according to thisinvention two glass plates are used. Electrically conductive parallellines are disposed on each plate with the electrically conductiveparallel lines on one plate extending orthogonally to the electricallyconductive parallel lines on the other plate. The parallel lines aredeposited on each plate with each plate extending beyond the ends of theparallel lines. Stated alternatively, the end of the parallel linesterminate a given distance from the edges of the glass plates. Aprotective glass coating is disposed over the parallel lines whichcompletely covers the top, sides, and ends of these lines. A pair ofsuch glass plates are separated a given distance, and a sealing materialis disposed between the glass plates around the periphery thereof. Theassembly is fired in an oven to seal the glass plates together andthereby form a chamber therebetween. The protective glass coating isremoved from the end or terminal regions of the parallel lines therebyto expose such end or terminal regions as electrical contacts. Theparallel lines are thus protected from attack and destruction duringpanel fabrication. If it is desired to have the parallel lines terminateflush with the edges of the glass plates, the glass plates then may becut back so that the end regions of the parallel lines are flush withthe trimmed edges of the glass plates. This may be desirable in somecases where electrical plugs or connectors require companion contacts ator nearthe edges of the glass plates.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of a preferred embodiment of the invention, as illustratedin the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a gaspanel constructed according to the method of this invention.

FIG. 2 is a cross-sectional view taken on the line 2-2 of the lowerglass plate in FIG. 1.

FIG. 3 is a plan view of a portion of a glass plate showing conductorswhich have been attacked and destroyed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A gas panel constructedaccording to this invention is illustrated in FIG. 1, and it includes alower plate 14 and an upper plate 16 disposed as shown. These glassplates preferably are one-quarter of an inch thick. The two glass platesare separated a given distance and sealed around their periphery to forma chamber therebetween for holding an illuminable gas. A bifurcatedhollow glass tube 18 is used to evacuate the chamber and insert anilluminable gas under less than atmospheric pressure.

The upper glass plate 16 has parallel electrical conductors 41 through48 disposed on the underside, and the lower glass plate 14 has parallelelectrical conductors 51 through disposed on the upper surface. Theparallel electrical conductors 41 through 48 on the upper plate 16 aredisposed orthogonally to the parallel electrical conductors 51 through60 on the lower plate 14.

The electrical conductors 41 through 48 on the upper plate 16 and theelectrical conductors 51 through 60 on the lower plate 14 may bedeposited thereon by using any one of several well known techniques. Onesuitable method includes forming a laminate of parallel electricallines, and this technique is shown and described in copendingApplication Ser. No. 214,348 filed on Dec. 30, 1971, for Gas PanelFabrication by Peter H. l-Iaberland et al. This method, brieflysummarized, includes the steps of depositing successive coatings byvacumn metalization on each of e the plates 14 and 16. A layer ofchromium about 1,000A thick is deposited on each glass plate, and alayer of copper about l0 ,000A thick is deposited on the chromium layer.A second layer of chromium about 3 1,000A thick is deposited on thecopper coating. A layer of photoresist material is disposed on the upperlayer of chromium, and the photoresist material is exposed to a lightpattern of alternate dark and light parallel regions thereby to definethe parallel electrical conductors. After this exposure is made thephotoresist coating is developed, and this removes the exposedphotoresist material and leaves the photoresist material in theunexposed regions. The plates 14 and 16 are then placed in a solutionwhich etches the laminate between the unexposed regions of thephotoresist thereby to yield a plurality of laminated parallel lines.The remaining photoresist material is exposed and removed by developing.Then the upper layer of chromium is oxidized by baking in an oven, andthe resulting laminated parallel lines are covered with a glass coating.The resulting structure is illustrated in FIG. 2, which is acrosssectional view of the lower plate 14 taken on the line ing them allthe'way to the end of the respective glass plates. This is illustratedin FIG. 3 which is a plan view of a portion of the lower glass plate 14with the upper plate 16 removed. The conductors 51 through 60 weredeposited as illustrated to extend all the way to the right edge of theglass plate 14. The laminated parallel lines 51 through 60 in FIG. 3were covered with the glass coating 70 which was applied over all of theupper surface of the glass plate 14, as previously explained. However,the right ends of the laminated parallel lines 51 through 60, flush withthe right edge of the plate 14, were left exposed or uncovered by theglass coating 70. During a subsequent step when the glass plate 14 and16 were fired in an oven to unite them by reflowing a glass fritdisposed around their periphery, an undesirable reaction took place. Theexposed ends of the copper layer in the laminated parallel lines tookpart in a reaction which caused them, along with the adjacent layers ofchromium, to be attacked and eroded. The area of attack is shown by thedark areas at the right of the parallel lines 51 through 60 in FIG. 3.The end region of the copper in the various parallel lines 51 through 60was pitted to varying degrees, and'in some cases the entire layer ofcopper in one or more parallel lines was eroded away from the edge ofthe glass plate 14 as illustrated by the parallel line 56 in FIG. 3.

The regions of the copper layer near the right edge of the glass plate14 in FIG. 3 are used as electrical contacts, and it is important toassure that the copper layer of each laminated parallel line remainssubstantially uniform in width and thickness, free of pitting orcomplete erosion. The condition in FIG. 3 makes electrical connectionsunreliable and hence reduces the operating capability of the gas panel.

In order to overcome the problem of pitting or erosion at the right endsof the laminated parallel lines 51 through 60 in FIG. 3, the glass plate14 is extended to the right so that the laminated parallel lines 51through 60 terminate one-quarter of an inch from the right edge of theplate 14 in FIG. 3. This is shown in FIG. 1 with the laminated parallellines 51 through terminating a given distance to the left of the rightedge of the lower plate 14. Likewise, the left ends of the laminatedparallel lines 51 through 60 in FIG. 1 do not extend all the way to theleft edge of the lower plate 14. The laminated parallel lines 41 through48 on the bottom edge of the upper plate 16 do not extend all the way tothe left and right edges of this plate. Consequently, the glass coating70 in FIG. 2 covers completely the ends as well as the sides and top ofeach one of the laminated parallel lines 51 through 60 in FIG. 1 sinceit extends over all of the'upper surface of the plate 14. A similarglass coating extends over all areas of the lower surface of the plate16 and covers completely the ends as well as the sides and the outersurface of all of the laminated parallel lines 41 through 48. Therefore,when a subsequent firing operation takes place to seal the plates 14 and16 together, the end regions of the laminated parallel lines areprotected by the glass coating which completely surrounds the endregions of all such parallel lines, and the undesirable reaction andattack on the terminal regions of the laminated conductor is prevented.

After the protective glass coating 70 in FIG. 2 is thus applied to theupper surface of the glass plate 14 and a similar glass coating isapplied to the lower surface of the glass plate 16 in FIG. 1, theseplates are spaced a given distance apart, and a sealing material isdisposed between and around the periphery of the plates 14 and 16. Theassembly is tired in an oven to seal the plates 14 and 16 together. Theresulting chamber formed between the glass plates 14 and 16 is evacuatedthrough the tubulation 18, and the chamber is filled with an illuminablegas after which the tubulation is tipped off. The method of spacing,sealing, evacuating the chamber, and filling with an illuminable'gas maybe performed by any one of several different techniques, but a preferredtechnique is illustrated and described in copending application Ser. No.214,348 filed on Dec. 30, 1971 for Gas Panel Fabrication by Peter H.Haberland et al.

Next the glass coating 70 in FIG. 2 and the outer layer of chromium areremoved in the terminal regions of the parallel lines 51 through 60 inFIG. 1 to expose the end regions of the copper lands as electricalcontacts. This removal of the glass coating and the outer layer ofchromium mayextend from the right ends of the parallel lines 51 through60 inFIG. 1 to the left any desired distance with the maximum distancebeing the right edge of the upper glass plate 16. Likewise, the glasscoating and the outer chromium layer of each of the laminated parallellines 41 through 48 is removed from the lower surface of the plate 16from the left edge any desired distance to the right with the maximumdistance being up to the left edge of the lower glass plate 14, therebyto expose the copper lands of the laminated parallel lines 41 through 48as electrical connect them to driving circuits not shown which energizethe conductors 41 through 48 to operate the gas panel. A similarelectrical plug or connector arrangement, not shown, may be used toengage the exposed copper lands of the parallel lines 51 through 60 andconnect them to driver circuits not shown which energize the parallellines 51 through 60 to operate the gas panel. The electrical connectorfor the lower plate 14 may be detachably connected to this plate withcompanion electrical contacts which extend over the top of the glassplate 14 and engage the copper lands of the respective parallel lines 51through 60. In some instances the electrical plug or contact arrangementrequires that the copper lands of the parallel lines 51 through 60extend all the way to the right edge of the glass plate 14. In suchcase, the portion of the glass plate 14 to the right of the terminationsof the lines 51 through 60 may be severed. The plate 14 may be cut alongthe dotted line 80. In this case the ends of exposed copper lands of theparallel lines 51 through 60 extend to the right, and they flush withthe right edge of the lower plate 14 whereby electrical plugs orconnectors which require this construction may be suitably employed.Likewise, the left end of the upper plate 16 may be severed, or not,depending upon the type of electrical plug or connector employed.

It is seen that a unique and novel technique is provided according tothis invention for fabricating a gas panel which completely protects theends of the copper lands of the parallel lines 41 through 48 of theupper plate 16 and the parallel lines 51 through 60 of the lower plate14 in FIG. 1 during the fabrication of the gas panel, and the exposedcopper lands of these parallel conductors may be terminated flush withor a given distance back from the edges of the glass plates as requiredby an electrical plug or connector. Thus the proper thickness and lengthof the copper lands as well as the proper electrical conductivity of theelectrical lands is assured.

While the invention has been particularly shown and described withreference to a preferred embodiment thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention.

What is claimed is:

l. A method of fabricating a gas panel which includes a pair oftransparent plates having parallel lines which serve as electricalconductors placed on each transparent plate with the parallel lines ofone transparent plate extending orthogonally to the parallel lines ofthe other transparent plate, the transparent plates being spaced apartand sealed together to form a chamber therebetween for holding anilluminable gas, the improved method of fabrication comprising the stepsof:

l. disposing the parallel lines on each transparent plate with the endsof the parallel lines terminating a given distance from the edges ofeach transparent plate so that each such transparent plateextends beyondthe ends of the parallel lines,

2. covering entirely the parallel lines on each transparent plate overthe top, sides and ends with a protective coating which protects theparallel lines from corrosion or attack during subsequent heatingoperations, and

3. removing the protective coating on each transparent plate after theheating operations from the top of the parallel lines at least at oneend thereof back a given distance from such end thereby to expose suchtop regions of the parallel lines as electrical contacts.

2. The method of claim I further including the step of cutting off atleast one edge of each transparent plate flush with the ends of theparallel lines having exposed top regions thereby to facilitate themating of the exposed top regions of the parallel lines as electricalcontacts with an electrical connector.

3. A method of fabricating a gas panel which includes a pair oftransparent plates having electrical lines which serve as electricalconductors placed parallel to one another on each transparent plate withthe electrical lines of one transparent plate extending orthogonally tothe electrical lines of the other transparent plate, the transparentplates being spaced apart and sealed together to form a chambertherebetween for holding an illuminable gas, the improved method offabrication comprising the steps of:

l. disposing the electrical lines on each transparent plate with theends of the electrical lines terminating a given distance from the edgeof each transparent plate so that each such transparent plate extendsbeyond the ends of the electrical lines,

2. covering the electrical lines over the top, sides and ends with aprotective coating which protects the electrical lines from corrosion orattack during subsequent heating operations, and

3. removing the protective coating from the top region of eachelectrical line at least at one end thereof back a given distance fromsuch end after the heating operations thereby to expose such top regionsof the electrical lines as electrical contacts.

4. The method of claim 3 further including the step of cutting off atleast one edge of each transparent plate flush with the ends of theelectrical lines having exposed top regions thereby to facilitate themating of the exposed top regions of the parallel lines as electricalcontacts with an electrical connector.

1. A method of fabricating a gas panel which includes a pair oftransparent plates having parallel lines which serve as electricalconductors placed on each transparent plate with the parallel lines ofone transparent plate extending orthogonally to the parallel lines ofthe other transparent plate, the transparent plates being spaced apartand sealed together to form a chamber therebetween for holding anilluminable gas, the improved method of fabrication comprising the stepsof:
 1. disposing the parallel lines on each transparent plate with theends of the parallel lines terminating a given distance from the edgesof each transparent plate so that each such transparent plate extendsbeyond the ends of the parallel lines,
 2. covering entirely the parallellines on each transparent plate over the top, sides and ends with aprotective coating which protects the parallel lines from corrosion orattack during subsequent heating operations, and
 3. removing theprotective coating on each transparent plate after the heatingoperations from the top of the parallel lines at least at one endthereof back a given distance from such end thereby to expose such topregions of the parallel lines as electrical contacts.
 2. coveringentirely the parallel lines on each transparent plate over the top,sides and ends with a protective coating which protects the parallellines from corrosion or attack during subsequent heating operations, and2. The method of claim 1 further including the step of cutting off atleast one edge of each transparent plate flush with the ends of theparallel lines having exposed top regions thereby to facilitate themating of the exposed top regions of the parallel lines as electricalcontacts with an electrical connector.
 2. covering the electrical linesover the top, sides and ends with a protective coating which protectsthe electrical lines from corrosion or attack during subsequent heatingoperations, and
 3. A method of fabricating a gas panel which includes apair of transparent plates having electrical lines which serve aselectrical conductors placed parallel to one another on each transparentplate with the electrical lines of one transparent plate extendingorthogonally to the electrical lines of the other transparent plate, thetransparent plates being spaced apart and sealed together to form achamber therebetween for holding an illuminable gas, the improved methodof fabrication comprising the steps of:
 3. removing the protectivecoating from the top region of each electrical line at least at one endthereof back a given distance from such end after the heating operationsthereby to expose such top regions of the electrical lines as electricalcontacts.
 3. removing the protective coating on each transparent plateafter the heating operations from the top of the parallel lines at leastat one end thereof back a given distance from such end thereby to exposesuch top regions of the parallel lines as electrical contacts.
 4. Themethod of claim 3 further including the step of cutting off at least oneedge of each transparent plate flush with the ends of the electricallines having exposed top regions thereby to facilitate the mating of theexposed top regions of the parallel lines as electrical contacts with anelectrical connector.